BEIRUT/MOSCOW (Reuters) – Syrian government forces have raised their flag over the last rebel bastion in eastern Ghouta, taking full control of the town of Douma as insurgents withdraw, Russian news agencies reported on Thursday, sealing a major victory for President Bashar al-Assad.

Eastern Ghouta had been the biggest rebel stronghold near Damascus, but insurgent groups there surrendered after a series of ferocious government assaults aided by Russia under a massive bombardment.

The Jaish al-Islam group in Douma agreed on Sunday to withdraw, hours after a suspected chemical weapons attack on the town that has raised the prospect of U.S. strikes. The Syrian government and Russia have called reports of the attack bogus.

“The raised state flag over a building in the town of Douma has heralded the control over this location and therefore over the whole of eastern Ghouta,” Major-General Yuri Yevtushenko, head of the Russian Peace and Reconciliation Center in Syria, was quoted as saying by Russian news agencies.

Russian military police were deployed in Douma on Thursday in accordance with the rebel surrender deal, Russia’s RIA news agency reported. Some 40,000 people, including thousands of rebels and their families, are leaving Douma for opposition areas in northern Syria under the agreement.

Iran Stands by Assad

On Wednesday, a top official from Iran, Assad’s other main ally, toured eastern Ghouta and vowed to stand by Syria in the face of “any foreign aggression.”

“Syria’s enemies are angry because of its military advances against terrorist groups,” Ali Akbar Velayati, Supreme Leader Ali Khamenei’s top adviser, told Iranian state TV during his visit to eastern Ghouta’s bomb-shattered ruins.

On Wednesday, U.S. President Donald Trump said that American missiles “will be coming” to Syria as he and other Western countries weigh military action over the suspected chemical attack in Douma.

Both Syria and Russia have said reports of the attack were fabricated by rebels and rescue workers in the town and have accused the U.S. of seeking to use it as a pretext to attack the government.

Bouthaina Shaaban, a top adviser to Assad, described the army’s recapture of eastern Ghouta as a “decisive point” in an interview on Wednesday, saying the rebels’ defeat had pushed the West to wage “psychological war” by threatening strikes.

“Consultations are ongoing between the allies and they will not let matters progress as Washington wants,” she told Lebanon’s al-Mayadeen channel, referring to the alliance of Assad, Russia, Iran and the Lebanese Shi’ite group Hezbollah.

In his tweet on Wednesday, Trump referred to Assad as a “gas killing animal”. The Syrian president on Wednesday made a public appearance with a group from an international Muslim body in Damascus.